1. Field of the Invention
The present invention relates to a method of manufacturing a device having an element (hereinafter referred to as luminous element) that is comprised of a luminous material sandwiched between electrodes (the device will hereinafter be referred to as light-emitting device), or to a device having an element (hereinafter referred to as liquid crystal element) that is comprised of a liquid crystal sandwiched between electrodes (the device will hereinafter be referred to as liquid crystal display device). Note that a display device herein is a generic term referring to a light-emitting device and a liquid crystal display device.
2. Description of the Related Art
In recent years, development is proceeding in a light-emitting device (also called as a light-emitting diode or an EL display device) using a luminous element (hereinafter referred to as EL element) that utilizes a luminous material in which EL (Electro Luminescence) can be obtained (hereinafter referred to as EL material). The EL display device is composed of a structure that has an EL element constructed of an anode, a cathode, and an EL material sandwiched therebetween. By applying a voltage between the anode and the cathode to allow a current flow in the EL material, carriers re-couple to thereby make the EL element emit light. In other words, the EL display device is a display device that uses a luminous element which itself has a light-emitting ability. that is, it is self-emissive, and hence, unlike a liquid crystal display device, it does not need a back light. In addition, the EL display device has merits such as a wide field of vision, is light in weight, and a low power consumption.
Various kinds of applications employing such EL display devices are expected. In particular, because the thickness of the EL display device is thin, thereby being capable of making the EL display device light in weight, its usage in portable equipments is attracting much attention. Therefore, attempts have been made in forming a luminous element on a flexible plastic film.
However, the heat resistance of a plastic film is low, and therefore the highest temperature of a process must be lowered. As a result, the present situation is that a TFT having a good electric characteristic as when formed on a glass substrate cannot be manufactured. Thus, a high-performance display device employing a plastic film has not been realized.